000
FXUS63 KMPX 131810
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
110 PM CDT MON MAY 13 2013

.UPDATE...

18Z AVIATION DISCUSSION ADDED BELOW.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 426 AM CDT MON MAY 13 2013

FROST AND FREEZE CONDITIONS WELL UNDERWAY EARLY THIS MORNING ACROSS
THE WI CWA WITH HIGH PRESSURE OVERHEAD. TEMPERATURES NEAR FREEZING
STRETCH ALL THE WAY WEST TO KSTC. THE HIGH WILL GIVE WAY TODAY TO AN
ADVANCING WARM FRONT... CURRENTLY LOCATED OVER THE WESTERN DAKOTAS.
SHORT TERM MODEL FORECASTS ARE OVERDONE ON PRECIPITATION THIS
MORNING JUST AHEAD OF THE WARM FRONT. OBSERVATIONS INDICATE MID
LEVEL CLOUDS WITH BASES ABOVE 10K. SURFACE DEW POINT FORECASTS ARE
ALSO NEARLY 10 DEGREES TOO HIGH IN THE DAKOTAS AS WELL. THIS IS A
PROBLEM WE HAVE NOTED FOR SEVERAL DAYS NOW. THIS DOES NOT BODE WELL
FOR THE DAY AHEAD. WE CONTINUED TO REFINE THE DEW POINT FORECAST FOR
TODAY WITH THE AFTERNOON MINIMUM HUMIDITY FALLING INTO THE 25 TO 35
PERCENT RANGE ACROSS THE FA. THE LOW END HUMIDITY VALUES ARE IN THE
MN RIVER VALLEY. CONTINUED TO FOLLOW THE SREF POPS BUT RESTRICTED
ANY MENTION OF SLIGHT CHANCE POPS OR HIGHER TO 3 HOURLY
PROBABILITIES OF 40 PERCENT OR GREATER FOR MORE THAN A HUNDREDTH OF
AN INCH. THE HIGH TEMPERATURE FORECAST TODAY IS A LITTLE PROBLEMATIC
DUE TO THE INCOMING CLOUDS AND PRECIP CHANCES. MIX DOWN TOOL FROM
VARIOUS MODEL SOLUTIONS POINTED TO A MUCH COOLER FORECAST FOR THE
EASTERN HALF OF THE FA. BLENDED THE MIX DOWN WITH CONSALL AND
OFFICIAL FOR THE DAY AHEAD.

PRECIPITATION CHANCES WILL END EARLY THIS EVENING IN OUR FAR
EASTERN WI COUNTIES. A MILD NIGHT IN STORE WITH LOWS IN THE 40S AND
50S. THE NEXT CONCERN IS A POTENTIAL CONVECTIVE COMPLEX FORMING OVER
NORTH DAKOTA DURING THE NIGHT WITH SOME SHOWERS PERHAPS REACHING OUR
NW CWA BEFORE DAYBREAK TUESDAY PER THE NMM WRF. WITH THE UNCERTAINTY
OF THIS FEATURE... KEPT POPS OUT FOR NOW WITH THE LONG TERM
FORECASTER ADDING SOME FOR TUESDAY MORNING.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 426 AM CDT MON MAY 13 2013

TUESDAY THROUGH SUNDAY...THERE ARE TWO MAIN ITEMS OF INTEREST IN THE
EXTENDED PERIOD. THE FIRST IS THE POTENTIAL FOR RECORD BREAKING
HEAT ON TUESDAY...WHICH MAY BE FOLLOWED BY A FEW STRONGER
THUNDERSTORMS BY THE EARLY EVENING. THE SECOND ITEM IS THE
TRANSITION TO A WETTER PATTERN TOWARDS THE WEEKEND AS SOUTHWEST
FLOW  DEVELOPS ACROSS THE REGION AHEAD OF THE NEXT UPPER LEVEL
TROUGH. WITH REGARDS TO THE HOT WEATHER ON TUESDAY...THERE IS
INCREASING EVIDENCE THAT THE MID LEVEL CLOUDS MAY DAMPER AN ATTEMPT
AT WIDESPREAD 90S ACROSS THE REGION. AS ALLUDED TO EARLIER...HAVE
ADDED SOME SLIGHT CHANCE POPS ACROSS THE FAR NORTHWESTERN CWA
TUESDAY MORNING. BOTH THE GFS AND NAM PLACE THE NOSE OF THE H925 LOW
LEVEL JET NEAR THE SD/ND/MN BORDER. THE GFS 13.00 IS THE MOST
AGGRESSIVE WITH THE SOUTHERN EXTENT OF THE PRECIP...BUT BOTH THE
SREF...AND ECMWF GENERATE QPF ACROSS THE NORTHWESTERN CWA. DEBRIS
CLOUDS FROM ANY CONVECTION THAT DOES FORM WOULD HINDER TUESDAY
TEMPERATURES. IN FACT...BOTH THE GFS AND NAM BUFR SOUNDINGS SHOW MID
LEVEL MOISTURE WITHIN THE 12-15KFT LEVEL...AND THE NAM IS NEARLY
SATURATED DURING THE PEAK HEATING HOURS. DESPITE THIS CONCERNING
CAVEAT...ONE CAN NOT IGNORE THE TIMING OF THE H850 THERMAL
RIDGE...WHICH BRINGS 20 TO 24C TEMPS ACROSS THE SOUTHERN HALF OF THE
CWA DURING THE AFTERNOON HOURS. SO...GIVEN THE CONFLICTING SOLUTIONS
DESCRIBED ABOVE...DID NOT MAKE A DRASTIC CHANGE TO
TEMPERATURES...BUT LOWERED THEM A DEGREE OR TWO. UNFORTUNATELY...THE
TWO MOST PROBABLE SOLUTIONS LIE ON OPPOSITE ENDS OF THE
SPECTRUM...BEING CLEAR SKIES AND MID 90S...OR HAZY SUNSHINE AND
UPPER 80S. ALSO...AS WE NEAR TUESDAY EVENING SOME OF THE SHORT RANGE
CONVECTIVE ALLOWING MODELS ARE SHOWING DEVELOPMENT ALONG THE MN/WI
BORDER. WILL HAVE TO CONTINUE TO WATCH THIS THREAT...SINCE MLCAPE
VALUES OF 2000J/KG TOGETHER WITH AMPLE DEEP LAYER SHEAR WOULD
SUPPORT SEVERE STORMS. HOWEVER CONVECTIVE INITIATION WILL BE
HAMPERED BY THE STRONG CAPPING THAT IS EXPECTED TO BE IN PLACE ALONG
AND AND AHEAD OF THE COLD FRONT.

LOOKING AHEAD....THE COLD FRONT WILL PASS THROUGH THE REGION AND
STALL OUT ACROSS IOWA. THIS WILL BRING DRY WEATHER...LIGHT
WINDS...AND SEASONABLE TEMPS FOR WEDNESDAY AND THURSDAY AS THE UPPER
MISSISSIPPI RIVER VALLEY REGION ENJOYS WEAK SUBSIDENCE BENEATH A
SLIGHTLY ANTICYCLONICALLY CURVED UPPER LEVEL JET. BY FRIDAY...BOTH THE
GFS AND ECMWF SHOW A +130KT JET AT 300MB CRASHING ONSHORE OVER
NORTHERN CALIFORNIA. AS THIS JET CARVES OUT AN UPPER LEVEL
TROUGH...LOW SOUTHERLY FLOW DOWNSTREAM WILL DRAW UP MOISTURE FROM
THE GULF ACROSS THE CENTRAL CONUS AND LIFT THE FRONTAL BOUNDARY
NORTHWARD AS A WARM FRONT. THE GFS REMAINS FASTER AND STRONGER
THAN THE ECMWF WITH THIS UPPER LEVEL TROUGH AND ASSOCIATED
SURFACE LOW...BUT CONTINUE WITH LIKELY POPS FOR THE WEEKEND...AND
WILL CONTINUE TO EVALUATE THE SEVERE POTENTIAL AS THE MODELS COME
INTO BETTER AGREEMENT WITH THE TIMING AND LOCATION OF THE
SYNOPTIC/MESOSCALE FEATURES.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 110 CDT MON MAY 13 2013

STRONG WAA AROUND 850 MB HAS AREA OF -SHRA OVER ERN MN NOW PUSHING
INTO WRN WI. DESPITE A GOOD 10K FT LAYER OF DRY AIR ABOVE THE
SFC...RAIN HAS BEEN ABLE TO FIGHT ITS WAY TO THE GROUND THIS
MORNING...SO INCLUDED A COUPLE HOUR LONG MENTION OF -SHRA AT WI
TERMINALS...THOUGH WITH SAFELY VFR CONDS. WARM FRONT AT 18Z FROM
ABOUT MITCHELL...SD TO AROUND JAMESTOWN...ND. THIS LOOKS TO ENTER
WRN MN AROUND 21Z AND PUSH TO ABOUT THE MN/WI BORDER BY 12Z BEFORE
LOSING ITS DEFINITION. THIS WILL ALLOW WINDS AT MN TERMINALS TO
BECOME MORE WRLY TONIGHT...BEFORE GOING BACK TO THE SSE TUE MORNING
IN RESPONSE TO AN AREA OF LOW PRESSURE MOVING ACROSS THE CANADIAN
PRAIRIES. AS GRADIENT TIGHTENS...S WINDS WILL INCREASE AND BECOME
GUSTY AGAIN ACROSS MN TUE MORNING. COLD FRONT WILL BE MOVING INTO
WRN MN AROUND 18Z TUES AND WILL MOVE INTO THE TWIN CITIES BY
AROUND 00Z. FOLLOWING THE IDEA OF THE 12Z NAM THAT ANY
PRECIPITATION TONIGHT WILL STAY NORTH OF THE MPX AREA ON NOSE OF
LLJ.

KMSP...ANY RAIN SHOULD BE DONE BY 19Z. WITH ALL THE DRY AIR IN
PLACE...CONFIDENCE REMAINS HIGH THAT VIS AND CIG RESTRICTIONS
WILL REMAIN SAFELY VFR. CONFIDENCE IN WIND DIRECTION FORECAST
DOES DIMINISH FOR TONIGHT...AS PASSAGE OF WARM FRONT WILL COINCIDE
WITH A CONSIDERABLE SLACKENING OF THE GRADIENT. STILL ALL GUIDANCE
POINT TO WEST WINDS DEVELOPING OVERNIGHT THAT TRANSITION BACK TO
THE SSE BETWEEN 12Z AND 15Z. COLD FRONT WITH WIND SHIFT TO THE
WEST LOOKS TO ARRIVE BETWEEN 22Z AND 00Z. GIVEN STRENGTH OF CAP
IN PLACE AHEAD OF THE FRONT...CONFIDENCE IS HIGH THAT MSP WILL NOT
SEE ANY TSRA ACTIVITY WITH THIS FRONT...JUST A WIND SHIFT.

/OUTLOOK FOR KMSP/
WED...VFR. NW WINDS 10 KTS.
THU...VFR. WINDS W 5 KTS.
FRI...MVFR POSSIBLE WITH CHC -TSRA. WINDS SE 5-10 KTS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
     EVENING FOR MNZ041>045-047>070-073>077-082>085-091>093.

WI...NONE.
&&

$$

SHORT TERM...RAH
LONG TERM...JRB
AVIATION...MPG